1. Field of the Invention
The invention relates to a method for treating foil for use in electrolytic capacitors, notably with aluminum foil, which foil is etched and then formed for use as anode and is etched but not formed for use as cathode.
The invention further relates to the resulting foil and to a device for continuously measuring the capacitance of foil moving through the treatment liquid.
2. Description of the Prior Art
In German Auslegeschrift No. 22 46 421 a measuring method and a device suitable therefor are described for the continuous measurement of the capacitance of aluminium foil during processing.
The measurement of the impedance of the foil according to the German Auslegeschrift takes place at the foil which is unwound from a reel and moves through the treatment liquid between said foil and electrodes present on either side thereof. The principle of the measuring arrangement is shown diagrammatically in FIG. 1 of the accompanying drawing. The foil is denoted by 1, the two electrodes by 2 and 3. The impedance Z is measured at 4.
For a continuous measurement of the capacitance for control during the etching process, for which there is a great need, and of the capacitance during forming at low voltage values, the device according to the German Auslegeschrift is less suitable because the measured result in that case is correct only when the capacitance of the measuring electrodes is very much larger than that of the foil.